This invention relates in general to inertial arresting devices and in particular to a device for use in an integrated circuit test handling and sorting apparatus that rapidly brings a free falling integrated circuit to a bounce-free stop at a test site, holds it at the site during the test, and then releases it for further processing.
In the manufacture of integrated circuits (IC's) and the like, it is important to test each IC reliably and at a high throughput rate. Typically modern IC testers operate at rates in excess of 5,000 IC's per hour with each IC being tested in an interval of approximately 100 milliseconds. In addition to these time constraints, the design of a successful, high-speed IC tester should take into account that (1) the most effective feeding arrangement uses a generally vertical free fall along a test path and (2) the free-falling IC must be stopped at a test site having a precisely known location. One problem inherent in this design approach is that if the falling IC strikes a rigid member that stops and locates it at a test site, the IC will bounce up from that member. If the test must wait for the IC to "settle down" on the member, this delay will significantly slow the production speed of the entire tester. Another problem is that the IC's usually have rectilinear, box-like ceramic bodies that are easily chipped. If they strike a fixed, rigid surface with a corner of the body, there is a significant likelihood that the IC will be damaged.
U.S. Pat. No. 4,000,798, issued to one of the present inventors, describes a prior solution to the "bounce" problem. A pivoted "foot" projects into the free fall path to provide a rigid stop member that locates an IC at the test site. Just before the falling IC lands on the foot, however, it strikes a pendulum mass. This impact absorbs a portion of the kinetic energy of the falling IC. The impacted pendulum swings away from the IC, strikes an abutment surface, and returns to clamp the IC against a rail member. Where the IC has a particularly large mass, this clamping is important to hold the IC on the foot. While this arrangement has worked very well in commercially successful handler/testers, it does not address the further problem of arresting the fall of "misaligned" IC's without damage. Also, this pendulum arrangement does not deal as well as possible with the problem of handling IC's of varying mass and size and it is not as cost effective as desired.
It is therefore a principal object of the present invention to provide an arresting device that rapidly brings a free-falling IC to a bounce-free stop at an accurately known location without damaging the IC, even when it is oriented during its fall so that it lands on one of its corners.
Another object is to provide an arresting device with the foregoing advantages that can accommodate IC's of any standard mass or size.
A further object is to provide an arresting device with the foregoing advantages that has a comparatively low cost of manufacture.